I'm with Mario on tough not describing many of the noir
protagonists. I doubt any of us doubts David Goodis's noir
credentials, but few of his characters could be thought of as
tough by thought or action. Many are just losers circling the
bowl waiting for someone to flush.

Close to the Lankford criteria and mirroring your comment,
Mark, is Paul Duncan's (NOIR FICTION) distinction between a
noir protagonist and a hardboiled one. Duncan says that a
hardboiled protagonist is likely to be teetering on the edge
of the abyss, while the noir protagonist is drowning in it.
Duncan was a rara-avis member many moons ago. I recommend his
NOIR FICTION.